One type of capacitor used in integrated circuits is a planar metal-insulator-metal (MIM) capacitor. A planar MIM capacitor includes a MIM dielectric between a top plate electrode and a bottom plate electrode. MIM capacitors are commonly used in decoupling and bypass applications.
Generally, a planar MIM capacitor may be unreliable and subject to premature breakdown when integrated over copper using a typical backend damascene process integration because of defects in the inter-level dielectric (ILD) between the copper and the planar MIM capacitor. Defects arising from, for example, topography, roughness, grain instability, and oxidation of the copper have all been variably identified as causes of the reliability failures. To avoid such issues, the MIM layout has been excluded from directly overlaying copper structures. Unfortunately, this can be a severe penalty against available on-chip MIM area; thus limiting the capacitance which can be created for decoupling and bypass applications. Thus, a need exists to control defects in a MIM capacitor when formed over copper.
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve the understanding of the embodiments of the present invention.